This invention relates generally to the field of optical devices, and more specifically to a reconfigurable optical switch and method.
Photonic crystals may be used to manipulate light in optical devices, such as photonic bandgap devices. A photonic crystal typically includes regions periodically composed of materials with different refractive indices. The periodic changes in the refractive index of the crystal prevent light within a certain range or xe2x80x9cbandxe2x80x9d of frequencies from entering or leaving the crystal. The band of frequencies that cannot propagate through the crystal may be referred to as a xe2x80x9cbandgap.xe2x80x9d To allow light within this band of frequencies to pass through certain paths in the photonic crystal, defects are created in the crystal. These defects represent points where the periodic changes in the refractive index of the crystal have been interrupted, which breaks the symmetry of the crystal. As a result of these defects, light may exist in localized states within the bandgap. Sequences of defects allow light within the bandgap to propagate through the crystal in paths created by the defects. These paths may be referred to as xe2x80x9cwaveguides.xe2x80x9d The waveguides control how light is transported through the crystal, so the waveguides control how the optical device operates.
According to the present invention, problems and disadvantages associated with previous optical switches and methods have been substantially reduced or eliminated.
In one embodiment of the invention, an optical switch includes a photonic crystal and a controller. The photonic crystal includes a first path having a plurality of first regions. At least one of the first regions is set to a first state to allow an optical signal to propagate through at least a portion of the crystal. The photonic crystal also includes a second path having a plurality of second regions. At least one of the second regions is set to the first state. The photonic crystal further includes a third path coupling the first path and the second path and providing the optical signal for propagation through at least one of the first and second paths. In addition, the photonic crystal includes a first actuator coupled to at least one of the first regions, and a second actuator coupled to at least one of the second regions. The controller is coupled to the first and second actuators. The controller is operable to switch the first and second regions between the first state and a second state. The second state reduces the propagation of the optical signal through at least a portion of the crystal.
In another embodiment of the invention, a photonic crystal includes a first path having a plurality of first regions. At least one of the first regions is set to a first state to allow an optical signal to propagate through at least a portion of the crystal. The photonic crystal also includes a second path having a plurality of second regions. At least one of the second regions is set to the first state. The photonic crystal further includes a third path coupling the first path and the second path and providing the optical signal for propagation through at least one of the first and second paths. The photonic crystal also includes a first actuator coupled to at least one of the first regions. The first actuator is operable to switch the first region between the first state and a second state. The second state reduces the propagation of the optical signal through at least a portion of the crystal. In addition, the photonic crystal includes a second actuator coupled to at least one of the second regions. The second actuator is operable to switch the second region between the first state and the second state.
In yet another embodiment of the invention, a method for reconfiguring an optical switch includes selecting a first path through a photonic crystal. The crystal includes the first path and a second path. The first path includes a plurality of first regions, and the second path includes a plurality of second regions. The crystal also includes a third path coupling the first path and the second path and providing an optical signal for propagation through one of the first and second paths. The method also includes heating at least one of the first regions and at least one of the second regions. The method further includes cooling the first region at a first rate to place the first region in a first state. The first state allows propagation of the optical signal through at least a portion of the crystal. In addition, the method includes cooling the second region at a second rate to place the second region in a second state. The second state reduces the propagation of the optical signal through at least a portion of the crystal.
Numerous technical advantages are provided according to various embodiments of the present invention. Particular embodiments of the invention may exhibit none, some, or all of the following advantages depending on the implementation. For example, the present invention may allow waveguides in an optical switch to be reconfigured. In one embodiment, a photonic crystal includes rods of a material, such as a chalcogenide. At least one of the rods may switch between a first state and a second state. In the first state, a defect forms in the photonic crystal, and an optical signal may propagate through at least a portion of the crystal. In the second state, no defect forms around the rod, which reduces the propagation of the optical signal through at least a portion of the crystal. In a particular embodiment, a defect may be formed by heating a rod and cooling the rod at one rate, and a defect may be removed by heating the rod and cooling the rod at another rate. By switching the states of the rods, the present invention allows the waveguides in a photonic crystal to be reconfigured. This allows the optical switch to be reconfigured so that the switch may route optical signals to different destinations.
The present invention may also allow the waveguides in the optical switch to be reconfigured more easily than conventional systems. For example, the present invention may vary the refractive index of the rods to a greater degree than previous systems could achieve. The present invention may also change the refractive index of the rods faster than conventional systems.
Other technical advantages are readily apparent to one of skill in the art from the attached figures, description, and claims.